The improved apparatus is particularly suited for heating and cooling of the plasticizer tube of an extruder for thermoplastics, although it will be appreciated that it may have other applications. In extruders of the type mentioned, control of the temperature of the plastic is important since although initially the extruding chamber may require heat to soften the plastic to extrudable condition, consideration must be given to the heat energy developed as a result of the friction of the plastic particles driven fowardly by the extruding screw. Thus, unless the temperature of the plasticizing tube is not carefully controlled, an excess amount of heat may have an adverse effect on the plastic being extruded.
Heating and cooling arrangements for extruding apparatus are within the prior art but in some cases require adaptation of the extruding tube to accomodate the same. Band type arrangements have also been proposed but these, insofar as I am aware, utilized heat sink structures, like metallic shoes, between the heating and cooling means and the extruder tube, and therefore required a number of parts which were expensive to produce and difficult to assemble.
My invention utilizes a plurality of identical cast metal shoes, and thus eliminates need for a plurality of different molds, as well as storage of multiple parts. The heating or cooling means are embedded in the casting to provide the ultimate in thermal transfer. Each of the shoes has means at its opposite sides to provide for quick and easy connection of the shoes in side-by-side relation to form a band about the plasticizer tube.